1. Field of Invention
The present invention relates to a sheet metal drill bit for drilling burrless round holes in thin products, such as metal sheets, plastics, etc., and wherein the drill bit has a drill head comprised of an outer cutting edge and a stabilizing central drill bit extending centrally from the front face of the head, and wherein a concave well is defined between the outer cutting edge and the central drill bit.
2. Description of Prior Art
When drilling round holes through a thin layer of material, such as sheet metal or other type sheet material, it is common practice today to utilize hole saws. The drawback of such saws is that they can only drill holes to a minimum of about 3/4 inch diameter. When it is necessary to drill smaller holes this may be achieved by specially designed hole saws which are both expensive and unserviceable. An alternative method is to use a conventional fluted drill bit, but these bits wabble and make holes that are distorted and often with very sharp burrs on the side edge of the wall and on both sides of the sheet. It is also known to provide hole cutting saws with a centrally mounted drill with its cutting end extending beyond the plane of the circular series of cutting teeth of an annular tool to guide the annual tool in a more precise manner. Such a cutting saw is disclosed in U.S. Pat. No. 2,926,555.